Control system for rotatable gun platform and optical sight



May 13, 1969 H. HEIDER ET AL 3,443,476

CONTROL SYSTEM FOR ROTATABLJE GUN PLATFORM AND OPTICAL SIGHT FiledSept. 1. 1966 +15% AMPLIF R Ia IE BALLISTIC nom pg COMPUTER V l/ SIGNALSERVOMOTOR l3 GENERATOR RATE OF TURN SIGNAL GENERATOR octoct SERVOMOTORl6 SIGNAL GENERATOR I5 SIG NAL AMPLIFIER l8 GENERAmR 4 IaALLIsTIc nom mm4 2 COMPUTER l E I7 -A-'Inm ,1

SERVOMOTOR l3 AMPLIFIER IS;

Pnom RATE OF AMPLIFIER 2o TURN SIGNAL GE SERVOMOTOR l6 RATE GYRO 2VINVENTORS FIG.2.

Helmut Heider 8| Heimut Looss ATTORNEYS 3,443,476 Patented May 13, 1969Int. Cl. r41 /06 US. Cl. 89-41 6 Claims ABSTRACT OF THE DISCLOSURE Acontrol system for use with a rotatably mounted gun platform whichcarries a gun and an optical sight, the latter being rotatable on theplatform with respect to the gun. The control system includes twose-rvomotors, one for turning the sight with respect to the gun and theother for turning the platform, and two control circuits whose outputsare applied to the respective servomotors. The first control circuitcompares a signal representing the nominal value of the lead anglebetween the optical axis of the sight and the bore axis of the gun witha signal representing the actual instantaneous angle between the opticalaxis of the sight and the bore axis of the gun, and forms a differencesignal which is applied to the first-mentioned servomotor. The secondcontrol circuit derives a positioning signal from a nominal value whichis a function, with reversed algebraic sign, of the actual rate of turnof the sight, a nominal value which is a function of a predeterminedrate of turn, and a signal which is a function of the actual rate ofturn of the platform, this positioning signal being applied to the otherservomotor.

The present invention relates to a control system for a gun and gunsight arrangement in which the gun is mounted on a movable platform andthe gun sight is movable with respect to the gun, wherein a controlcircuit for controlling the turning of the platform is given a signalrepresenting a predetermined rate of turn.

When a gun is trained on a moving target, the latter is normallyobserved through an optical sighting device hereinafter referred tosimply as a sightwhich is coaxial with the gun, the gun and the sightbeing kept trained on the target by the application of a signal whichkeeps the gun turning at the proper rate. If the gun and the sight areon a common platform, for example, the turret of a tank, and if both areaimed by adjusting the azimuth and elevation of the base, thecorrectional angles, such as lead and elevational angles which aredetermined, for example, by a ballistic computer, can be set only bychanging the position of the sight with respect to the gun. In this way,the gun remains trained on the target while the line of sight, i.e., theoptical axis of the sight, is moved off target, and this means that thesight has to be adjusted to remain trained on the target. Thus, by usingthe correction angles, the sight is first displaced with respect to thegun, after which the sight is again brought into alignment with thetarget due to the turning of the gun. This type of aiming is known asforming a dependout line of sight. In practice, this type of aimingmakes it difiicult to keep the gun trained on the target, and also makesit difficult to track a moving target. For this reason, too, the timeinterval between the instant the target is first acquired and the firingcommand can be given is relatively long.

It is, therefore, the primary object of the present invention to providea sight control arrangement which is simpler, more accurate andfaster-responding than the above-mentioned type of arrangement.

More particularly, it is the object of the invention to provide a systemin which the steps that have to be carried out to aim the gun arecarried out not sequentially, as was heretofore the case, butsimultaneously.

Basically, the main difficulty involved in carrying out the stepsimultaneously is that both a correction angle and a rate are needed inorder to carry out the aiming steps simultaneously. Accordingly thepresent invention resides in a control system incorporating two controlcircuits, one of which compares a signal representing the nominal valueof the lead angle with a signal representing the actual instantaneousangle between the optical axis of the sight and the bore axis of the gunand forms a difference signal which is used to position the sight. Theother control circuit derives a setting signal for the platform from anominal value which is a function, with reversed algebraic sign, of theactual rate of turn of the sight, a nominal value which is a function ofa predetermined rate of turn, and a signal which is a function of theactual rate of turn of the platform.

With a ballistic correction angle being given, when a gun is aimed inaccordance with the present invention, the sight is turned while at thesame time the platform is rotated in the opposite direction and at thesame rate. In this way, the optical axis of the sight remains trained onthe target while the gun is rotated with respect to the sight throughoutan angle corresponding to the ballistic correction angle. In the case ofthe so-called independent sight, therefore, the sight does not have tobe adjusted after the gun has been trained on the target.

According to a further feature of the present invention, thesimultaneous displacement of the sight with respect to the platform andthe displacement of the platform with respect to the target is improvedby providing an auxiliary control circuit for the first control circuit,i.e., the control circuit which provides a signal for positioning thesight. The auxiliary circuit produces a positioning signal for the sightby comparing the actual rate of turn of the sight with the difference ofthe angular displacement of the sight which is a function of the angleof the displacement, the latter being a control signal which isdependent on the rate of turn of the sight. The last-mentioneddifference, after change of the algebraic sign, and a predeterminednominal rate of turn for the platform, are used to form a signal forturning the platform.

Additional objects and advantages of the present invention will becomeapparent upon consideration of the following description when taken inconjunction with the accompanying drawings in which:

FIGURE 1 is a block diagram of one embodiment of a control systemaccording to the present invention.

FIGURE 2 is a block diagram of another embodiment of a control systemaccording to the present invention.

Referring now to the drawings and first to FIGURE 1 thereof, the sameshows a weapon such as a gun 10 and an optical sight 11, both beingmounted on a common platform 12. The sight 11 can be turned with respectto the gun 10 and the platform 12 by means of a servomotor 13, the anglebetween the bore axis 10a of the gun 10 and the optical axis 11a of thesight 11 being reflected by a signal generator 14 which is mechanicallycoupled to the servo motor 13 and which puts out a signal that is afunction of the angle between the axes 10a and 11a. The rate at whichthe sight 11 is turned is measured by a further signal generator, suchas a tachometer-type generator 15. The platform 12 is rotated by meansof a further servomotor 16, the rate at which the platform turns beingsensed by a rate gyro 21. The further component parts of the system willbe described as the operation is explained.

A ballistic computer 17 determines a correction angle Atp and appliesthe same as a nominal value signal -A p to the first control circuit.This nominal value is compared with the actual angle Age formed betweenthe bore axis a of the gun 10 and the optical axis 11a of the sight 11,the signal representing this angle A being put out by the signalgenerator 14. The difference between these two values is amplified by anamplifier 18 and applied to the servomotor 13 such as to turn thesighting 11 until the difference is equal to zero. At the same time, thesignal A o which is the first derivative with respect to time of thesignal A o and hence a signal which is a function of and represents therate at which the sighting device 11 is turned, is taken off the signalgenerator 15 and, after inversion of the algebraic sign, applied to asecond control circuit, where it is added to a signal representing apredetermined angular velocity or rate of turn to, the same beingdetermined by the marksman in command of the gun and produced by anappropriate signal generator 17a. This value is compared with the actualrate (w+A sensed by the rate gyro 21, at which the platform 12 turns. Ifthe signals are dissimilar, a setting signal is applied to theservomotor 16 via a further amplifier 20, and the platform 12 continuesto turn until the difference between the signals becomes zero.

The algebraic sign of the correction signals are such that the sight 11is turned with respect to the gun 10 throughout an angular distancecorresponding to the determined correction angle, while simultaneouslythe platform 12 carrying the gun 10 and the sight 11 is turned in theopposite direction throughout the same angular distance so that, withrespect to the target, the optical axis of the sighting device 11remains stationary and the bore axis of the gun is turned through'thecorrectional angle.

The embodiment shown in FIGURE 2 differs from that of FIGURE 1 in thatthe first control circuit, which is a positional control circuit, hasassociated with it an auxiliary control circuit in the form of a speedcontrol circuit. The amplified signal representing the angulardifference between the sight 11 and the gun 10, which is put out by theamplifier 18, serves as the nominal value A for the rate of turn of thesight 11 with respect to the platform 12, this nominal value beingcompared with the actual rate of turn (-A ,5 taken off the signalgenerator 15. The difference between the two values is applied, via anamplifier 22, to the servomotor 13. At the same time, the predeterminedrate of turn A p' for the sight 11 is, after inversion of the algebraicsign, in the amplifier 19, applied to the second control circuit and isadded to the predetermined rate of turn w of the platform. Both valuesare compared with the actual rate of turn (w[Ao) which is taken off therate gyro 21. Any difference is amplified by amplifier as applied to theservomotor 16.

The arrangement shown in FIGURE 2 improves the simultaneous displacementof the sight 11 and the common platform 12. In practice, the dynamics ofthe auxiliary control circuit and that of the second control circuitshould be the same so as to achieve the desired simultaneity andtherefore particularly precise sighting and aiming.

Each of the individual components incorporated in the control systemsaccording to the present invention is, per se, known in the art. Therate of turn signal generator 17a is formed, for example, by apotentiometer, by the means of which a variable voltage can be produced.The handle of this potentiometer not shown here will be moved by thegunner correspondingly to the desired value of nom- The presentinvention is applicable for multiple-axis control, that is to say,separate control circuit systems can be provided for controlling bothazimuth and elevation.

What is claimed is:

1. In combination with a gun platform which is rotatably mounted on abase, a gun which is mounted on said platform for rotation therewith,and an optical sight which is also carried on said platform but which isrotatable with respect to the gun, a control system comprising, incombination:

(a) a first servomotor for turning the sight with respect to the gun;

(b) means forming a first control circuit for comparing a signalrepresenting the nominal value of the lead angle between the opticalaxis of the sight and the bore axis of the gun with a signalrepresenting the actual instantaneous angle between the optical axis ofthe sight and the bore axis of the gun and for forming a differencesignal, the latter being applied to said first servomotor;

(c) a second servomotor for turning the platform; and

(d) means forming a second control circuit for deriving a positioningsignal from a nominal value which is a function, with reversed algebraicsign, of the actual rate of turn of the sight, a nominal value which isa function of a predetermined rate of turn, and a signal which is afunction of the actual rate of turn of the platform, said positioningsignal being applied to said second servomotor.

2. The combination defined in claim 1 wherein said first control circuitcomprises:

(1) a first signal generator for producing a signal which is a functionof the angle between the optical axis of the sight and the bore axis ofthe gun;

(2) a ballistic computer for giving a nominal angle which is a functionof a predetermined correction angle; and

(3) means for producing an amplified difference between the outputs ofsaid first signal generator and of said computer and for applying thesame to said first servomotor.

3. The combination defined in claim 2 wherein said second controlcircuit comprises:

(4) a second signal generator for producing a signal which is a functionof the rate at which the sight is turned;

(5) means for producing a signal which is a function of a predeterminedrate of turn;

(6) a rate gyro for producing a signal which is a function of the actualrate of turn of the platform; and

(7) means for adding the outputs of said second signal generator and ofsaid means defined in paragraph (5), and for producing an amplifieddifference between the thus-obtained sum and the output of said rategyro and applying such difference to said second servomotor.

4. The combination defined in claim 1 wherein said first control circuitincludes a main circuit and an auxiliary circuit, the latter being ameans for comparing the actual rate of turn of the sight with thedifference of the angular displacement of the sight which is a functionof the angle of the angular displacement, the latter being a controlsignal which is dependent on the rate of turn of the sight, saidlast-mentioned difference, after change of algebraic sign, and apredetermined nominal rate of turn for the platform, being used to forma signal for turning the platform.

5. The combination defined in claim 4, wherein said first controlcircuit comprises:

(1) a first signal generator for producing a signal which is a functionof the angle between the optical axis of the sight and the bore axis ofthe gun;

(2) a ballistic computer for giving a nominal angle which is a functionof a predetermined correction angle;

(3) means for producing an amplified difference between the outputs ofsaid first signal generator and of said computer;

(4) a second signal generator for producing a signal which is a functionof the rate at which the sight is turned; and

(5) means for producing an amplified difference between the outputs ofsaid means defined in paragraph ference between the thus-obtained sumand the out- (3) and said second signal generator and for applyput ofsaid rate gyro and applying the last-mentioned thE same to 531d firstServomotofdifference to said second servomotor.

6. The combination defined in claim 5 wherein said second controlcircuit comprises: References Cited (6) means for producing a signalwhich is a function 5 UNITED STATES PATENTS of a predetermined rate ofturn,

(7) a rate gyro for producing a signal which is a 3,309,963 3/ 1967Salomonssonfunction of the actual rate of turn of the platform; d 10BENJAMIN A. BORCHELT, Primary Examiner.

(8) means for adding the amplified output of said 3 BENTLEY AssistantExaminer.

means defined in paragraph (3), with reversed algebraic sign, to theoutput of said means defined in X- paragraph (6), and for producing anamplified dif- 318-448 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3 ,443 ,476 May 13 1969 Helmut Heider et a1.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

In the heading to the patent, line 9, "P 1,270" should read P 12 7O449.3-15

Signed and sealed this 24th day of February 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. E.

Attesting Officer Commissioner of Patents

